﻿#pragma once
#include <iostream>
#include <vector>
using namespace std;
// 请完成哈希表的如下操作
// 哈希函数采用除留余数法﻿
template<class K>
struct HashFunc
{
	size_t operator()(const K& key)
	{
		return (size_t)key;
	}
};

// 哈希表中支持字符串的操作
template<>
struct HashFunc<string>
{
	size_t operator()(const string& key)
	{
		size_t hash = 0;
		for (auto e : key)
		{
			hash *= 31;
			hash += e;
		}

		return hash;
	}
};

// 以下采用开放定址法，即线性探测解决冲突
namespace open_address
{
	enum State
	{
		EXIST,
		EMPTY,
		DELETE

	};

	template<class K, class V>
	struct HashData
	{
		pair<K, V> _kv;
		State _state = EMPTY;
	};

	template<class K, class V, class Hash = HashFunc<K>>
	class HashTable
	{
	public:
		HashTable()
		{
			_tables.resize(__stl_next_prime(0));
		}
		inline unsigned long __stl_next_prime(unsigned long n)
		{
			// Note: assumes long is at least 32 bits.
			static const int __stl_num_primes = 28;
			static const unsigned long __stl_prime_list[__stl_num_primes] =
			{
				53, 97, 193, 389, 769,
				1543, 3079, 6151, 12289, 24593,
				49157, 98317, 196613, 393241, 786433,
				1572869, 3145739, 6291469, 12582917, 25165843,
				50331653, 100663319, 201326611, 402653189, 805306457,
				1610612741, 3221225473, 4294967291
			};
			const unsigned long* first = __stl_prime_list;
			const unsigned long* last = __stl_prime_list +
				__stl_num_primes;
			const unsigned long* pos = lower_bound(first, last, n);
			return pos == last ? *(last - 1) : *pos;
		}
		bool Insert(const pair<K, V>& kv)
		{
			//去重
			if (Find(kv.first))
				return false;
			//扩容
			if (_n * 10 / _tables.size() > 7)
			{
				HashTable<K, V> newtable;
				newtable._tables.resize(__stl_next_prime(_tables.size() + 1));
				for (int i = 0; i < _tables.size(); i++)
				{
					if (_tables[i]._state == EXIST)
					{
						newtable.Insert(_tables[i]._kv);
					}
				}
				_tables.swap(newtable._tables);
			}
			//主要插入过程
			Hash hash;
			size_t Hash0 = hash(kv.first) % _tables.size();
			while (_tables[Hash0]._state == EXIST)
			{
				++Hash0;
				Hash0 %= _tables.size();
			}
			_tables[Hash0]._kv = kv;
			_tables[Hash0]._state = EXIST;
			++_n;
			return true;
		}
		HashData<K, V>* Find(const K& key)
		{
			Hash hash;
			size_t Hash0 = hash(key) % _tables.size();
			while (_tables[Hash0]._state != EMPTY)
			{
				if (_tables[Hash0]._kv.first == key && _tables[Hash0]._state == EXIST)
					return &_tables[Hash0];
				++Hash0;
				Hash0 %= _tables.size();
			}
			return nullptr;
		}
		bool Erase(const K& key)
		{
			HashData<K, V>* PHashData = Find(key);
			if (PHashData == nullptr)  
				return false;

			PHashData->_state = DELETE;
			--_n;
			return true;
		}


	private:
		vector<HashData<K, V>> _tables;
		size_t _n = 0;  // 表中存储数据个数
	};
}